1. Field of the Invention
The present invention relates to an industrial platform, and, in particular, to a tray mounted on a pallet.
2. Description of the Prior Art
In order to understand the requirements for an improved pallet, it is necessary to have some knowledge of the field of materials handling. The handling of materials involves the individual motions required to move commodities. The individual motions include lifting, translation and patterns of lifting and translation. Commodities moved include solid and liquid materials packaged in containers. Pallets have facilitated the handling of containers when pallets are used in concert with fork lifts. The combination of pallets and fork lifts additionally simplifies the lifting and transverse movement of large heavy objects not in containers.
Wood has historically been the most widely used material of construction for pallets. The advantages of wooden pallets have been a low cost, repairability and a capacity to carry a great quantity of weight.
Wooden pallets have commonly been transported bearing purchased materials from one business location to another (i.e. a manufacturer's warehouse to a distributor's warehouse) in order to hasten unloading. When a purchased material is shipped on a wooden pallet, the pallet adds extra weight to the shipment in transit and the pallet mass occupies space that might otherwise be used to transport additional purchased merchandise.
These problems are compounded if by agreement between the parties, pallets are to be returned to the pallet owner. Such a return trip is costly to the parties. Additionally, inequitable substitutions have been made in wooden pallet return agreements. These substitutions have been possible because a pallet owner could not indisputably identify its pallets.
A pallet assembly proposed to solve the return transportation and inequitable substitution problems is described by the Carnwath U.S. Pat. No. 4,059,057 issued Feb. 22, 1977. The assembly includes a heavy duty permanent pallet portion and a low cost expendable pallet skid. Board elements of the skid rest in alignment with the set of board elements of the permanent pallet. Board elements of the pallet skid are not attached to the permanent pallet. The inexpensive pallet skid is transported with the purchased material and is not returned to the pallet owner.
Another expendable pallet portion and a permanent pallet portion assembly is described in the Weber U.S. Pat. No. 2,754,077 issued July 10, 1956. A requirement of disassembly at the pallet's destination is a distinguishing feature. Additionally, the expendable portion of the Weber pallet has a function of providing lateral support for wirebound boxes.
A pallet assembly containing a nesting feature is described in the Sanders U.S. Pat. No. 3,664,272 issued May 23, 1972. The patent describes a nestable pallet constructed of thin boards and a plurality of tapered legs. The purchased material is secured to the pallet by steel strapping, heavy duty tape or some similar means.
Another pallet assembly which addresses the transportation expense problem is described in the Candella U.S. Pat. No. 4,267,780, issued May 19, 1981. The patent describes a disposable pallet board to which a box is firmly secured by straps. The pallet board is relatively thin and has the same horizontal dimensions as that of the base pallet.
Plastic was introduced as a material of pallet construction because plastic pallets weigh less than wooden pallets. Also plastic pallets are molded to secure containers specially fashioned to hold particular products. Additionally, a plastic pallet owner can readily identify its pallets by color or specialty molding marks.
Plastic pallets cost substantially more than wooden pallets. Also, if plastic pallets crack or break, they usually cannot be repaired. Wooden pallets can usually be repaired by replacing a damaged wooden member. Lastly, plastic pallets cannot support as large a weight load as can wooden pallets.
A plastic pallet assembly proposed to improve strength and load supporting ability is described in the Kreeger U.S. Pat. No. 4,597,338 issued July 1, 1986. The patent describes a plastic pallet made from two identical molded pallet halves that are snapped together to form a pallet.
A pallet assembly which includes molded pallet construction secured to wooden support members is described in the Skinner U.S. Pat. No. 3,654,874 issued Apr. 11, 1972.
The pallet assemblies described have not been entirely satisfactory.